The invention relates to compounds useful in inhibiting fungal infections.
Fungal infections (mycoses) can contribute to and complicate many diseases, including pulmonary diseases and respiratory tract diseases. The number of instances of opportunistic fungal infections have increased, particularly in immunocompromised patients, such as those with AIDS, those undergoing chemotherapy for cancer, and those undergoing therapy to prevent graft rejection following organ transplant surgery.
In animals, fungal infections may be cutaneous, subcutaneous, or systemic. Superficial mycoses include tinea capitis, tinea corporis, tinea pedis, onychomycosis (e.g., nail fungus), perionychomycosis, pityriasis versicolor, oral thrush, and other candidoses such as vaginal, respiratory tract, biliary, eosophageal, and urinary tract candidoses. Systemic mycoses include systemic and mucocutaneous candidosis, cryptococcosis, aspergillosis, mucormycosis, paracoccidioidomycosis, North American blastomycosis, histoplasmosis, coccidioidomycosis, and sporotrichosis.
Plants are also susceptible to fungal infections. Plant diseases are caused by a myriad of invasive fungal pathogens which fall into many genera, for example: soft rot (e.g., Rhizopus spp.), leaf curl (e.g., Taphrina spp.), powdery mildew (e.g., Sphaerotheca spp.), leaf spots (e.g., Fulvia spp.), blight (e.g., Alternaria spp.), blast (e.g., Magnaporthe spp.), black rot (e.g., Guignardia spp.), scab (e.g., Venturia spp.), wilts (e.g., Fusarium spp.), rusts (e.g., Puccinia spp.), smuts (e.g., Ustilago spp.), and cankers (e.g., Rhizoctonia spp.).
Examples of pathogenic organisms include dermatophytes (e.g., Microsporum canis, M. gypseum, M. distortum, M. audouinii, M. ferrugineum, M. rivalieri, M. fulvum, M. cookei, M. vanbreuiseghemii, M. persicolor, Trichophyton rubrum, T. mentagrophytes, T. mengninii, T. nanum, T. schoenleinii, T. tonsurans, T. verrucosum, T. soudanense, T. violaceum, T. yaoundei, T. gourvilii, T. simii, T. ajelloi, Hendersonula toruloidea), yeasts (e.g., Candida albicans, C. tropicalis), Torulopsis glabrata, Epidermophyton floccosum, Malassezia furfur (Pityropsporon orbiculare, P. ovale), Cryptococcus neoformans, Aspergillus fumigatus and other Aspergillus spp., Zygomycetes (e.g., Rhizopus, Mucor), Paracoccidioides brasiliensis, Blastomyces dermatitidis, Histoplasma capuslatum, Coccidioides immitis, and Sporothrix schenckii. 
In one aspect, the invention features a substantially pure compound having the formula: 
wherein R1 is a hydroxyl group or a moiety that can be replaced by a hydroxyl group in a hydrolysis reaction; each R2 is, independently, H or a monovalent hydrocarbon moiety containing between 1 and 4 carbon atoms, inclusive; R3 is a pyrrole, furan, or thiophene ring; and X is an integer between 4 and 10, inclusive. In all of the compounds of the invention (Compounds I-V), the sum of the carbons on the R2 moieties is preferably less than 15. More preferably, the sum of the carbons on the R2 moieties is less than 9 and, most preferably, less than 5. Most preferably, each R2 is H or, alternatively, each R2 is, independently, H, CH3, or C2H5. In other preferred embodiments, R3 is a furan ring, and X is an integer between 5 and 7, inclusive. The claimed compounds are capable of inhibiting the growth of a fungal cell (e.g., a species of Candida or a dermatophyte). The compounds of the invention can be admixed with a pharmaceutically acceptable carrier to produce a pharmaceutical composition. In one preferred example, the composition is formulated for topical application.
In another aspect, the invention features a substantially pure compound having the formula: 
wherein R1 is OH, NH2, OCH3, or OC2H5; R3 is a pyrrole, furan, or thiophene ring; and X is an integer between 5 and 7, inclusive. In preferred compounds, R1 is OH and/or R3 is a furan ring. These compounds also can be provided as pharmaceutically acceptable compositions and used to inhibit the growth of fungal cells, e.g., to treat fungal infections in plants and animals, including humans. Preferably, the compound inhibits growth of fungal cells by at least 25%, more preferably by at least 50%, and most preferably by at least 90%, as determined by a standard assay described herein.
The compounds of the invention, in addition to being useful for treating fungal infections, can be used for preventing fungal infections.
Preferred compounds of within formula (II) have the formula: 
wherein X is an integer between 5 and 7, inclusive. These compounds can be isolated from a liquid culture of Anarhinnum. A preferred method includes the steps of (a) contacting a liquid culture of Anarrhinum to a DNA methylation inhibitor; (b) after at least three days, contacting the culture, or a subculture thereof, with an elicitor; and (c) extracting the compound from the elicitor-contacted culture, or a subculture thereof The method can also include, between step (a) and step (b), the step of subculturing the culture. Preferably, the liquid culture is subcultured at least twice. Alternatively, these compounds can be made by the steps of (a) initiating a callus culture from an Anarrhinum seed; (b) culturing the initiated callus culture; (c) initiating a liquid culture from the callus culture; (d) contacting the liquid culture with a DNA methylation inhibitor; (e) subculturing the DNA methylation inhibitor-contacted liquid culture; (f) contacting the subculture with an elicitor; and (g) extracting the compound from the elicitor-contacted culture, or a subculture thereof Neither the DNA-methylation inhibitor step nor the elicitor step are required in order for the Anarrhinum liquid culture to yield the compounds of the invention, inclusion of these steps will augment their yield.
In another aspect, the invention features a substantially pure compound having the formula: 
wherein R1 is a hydroxyl group or a moiety that can be replaced by a hydroxyl group in a hydrolysis reaction; each R2 is independently H or a monovalent hydrocarbon moiety containing between 1 and 4 carbon atons, inclusive; and X is an integer between 3 and 9, inclusive. These compounds are useful in inhibiting the growth of fungal cells, e.g., for the treatment or prevention of fungal infections in plants and animals, including humans.
In another aspect, the invention features a substantially pure compound having the formula: 
wherein R1 is a hydroxyl group or a moiety that can be replaced by a hydroxyl group in a hydrolysis reaction; each R2 is, independently, H or a monovalent hydrocarbon moiety containing between 1 and 4 carbon atons, inclusive; and X is an integer between 3 and 9, inclusive. These compounds are useful in inhibiting the growth of fungal cells, e.g., for the treatment or prevention of fungal infections in plants and animals, including humans.
The compounds of the invention exhibit broad antifungal activity and high specific activity, and are thus useful for the treatment or prevention of fungal infections in both plants and animals, including living animals and plants, and plant products (e.g., grain or feed). Animals include mammals, particularly humans, as well as domestic animals bred for food or as pets, such as horses, cows, sheep, poultry, fish, pigs, cats, dogs, and zoo animals. Plants include trees, crops, grasses, and flowering plants.
Other features and advantages of the invention will be apparent from the following description of the preferred embodiments thereof and from the claims.